1. Field of the Invention
The present invention relates to a heat treatment apparatus and a heat treatment method for heat-treating a thin plate-like precision electronic substrate, such as a semiconductor wafer and a glass substrate for a liquid crystal display device (hereinafter referred to simply as a “substrate”), which has a surface coated with a film such as a resist film.
2. Description of the Background Art
Products of semiconductor devices, liquid crystal display devices and the like are fabricated by performing a series of processes including cleaning, resist coating, exposure, development, etching, interlayer insulation film formation, heat treatment, dicing and the like on the aforementioned substrate. A substrate processing apparatus which performs, among the aforementioned processes, a resist coating process on a substrate to transfer the substrate to an exposure unit and which receives an exposed substrate from the exposure unit to perform a development process on the exposed substrate is widely used as what is called a coater-and-developer. U.S. Patent Application Publication No. 2009/060686 discloses an example of such a substrate processing apparatus.
As disclosed also in U.S. Patent Application Publication No. 2009/060686, a coater-and-developer performs a post-applied bake (PAB) process for performing a heating treatment on a substrate with a resist film formed thereon by a resist coating process to evaporate a solvent component in the resist. When a chemically amplified resist is used, the coater-and-developer performs a post-exposure bake (PEB) process on an exposed substrate to cause a reaction such as crosslinking, deprotection or decomposition and the like of resist resin to proceed using a product formed in a resist film by a photochemical reaction during the exposure process as an acid catalyst. After a development process, the coater-and-developer performs a hard bake (HB) process for heating a substrate to completely dry a patterned resist film. In this manner, the coater-and-developer performs heating treatments on films formed on a surface of a substrate for various purposes.
An attempt has also been made to perform such heating treatments of films by light-irradiation heating. For example, Japanese Patent Application Laid-Open No. 63-202025 (1988) discloses that a heating treatment is performed by irradiating a resist film formed by spin coating on a main surface of a substrate with infrared light. Also, Japanese Patent Application Laid-Open No. 2001-332484 discloses that a resist pattern subjected to a development process is irradiated with light from a flash lamp.
However, heating treatments performed on resist films formed on main surfaces of substrates by irradiation with light result in different heating treatment temperatures in some cases even when the resist films are irradiated with light at the same intensity because optical absorption characteristics differ depending on the types of resist films and resist patterns. As a result, there arises a problem such that process uniformity cannot be maintained between substrates. It is also very complicated to change the intensity of light for irradiation in accordance with the types of resist films and the like.